A rapid quantitative determination of acetaminophen in plasma

A simple method is described for the rapid, quantitative analysis of acetaminophen in plasma. The nonconjugated acetaminophen present in the plasma following drug administration is determined after plasma protein precipitation by high-pressure liquid chromatography (HPLC) at a wavelength of 240 nm. Acetaminophen (I) is detectable at levels as low as 0.1 microgram/ml. Mean recoveries of 94% with a coefficient of variation of 3% were obtained for plasma standards whose concentrations ranged from 0 to 32 microgram/ml. Interassay variability of the slope of the standard curve had a coefficient of variation of 2.7%. Application and verification of this method by comparison with another procedure run simultaneously during several human bioavailability studies are described.